Phase Shift Induced Degradation of Polarization Caused by Bends in Inhibited-Coupling Guiding Hollow-Core Fibers

We report on a comprehensive analysis of the polarization-maintaining (PM) behavior of two different kinds of inhibited-coupling (IC) guiding hollow-core fibers and the influence of fiber bends. A phase shift induced degradation of the incident linear polarization state was observed due to a mismatch of the propagation constants of the orthogonally polarized LP01-modes of the fiber. This effect was predicted theoretically and is corroborated with numerical simulations and experimental results. It is shown that the phase shift is enhanced by a reduction of the bending radius of the fiber but can be circumvented by orienting the polarization of the injected beam either parallel or perpendicular to the plane of bending.